NumberDrop - A uniquely challenging math puzzle game.
MathIsFun Times Table - Learn Your Multiplication Tables
dworksheets.com - Free K-12 math worksheets to assist students, teachers, parents & tutors to practice, teach or prepare grade school assignments, classwork or homework questions & answers is available online in printable & downloadable format.
GCompris - Educational Game for Children 2 to 10 years old.
Sum Fun - A fun number puzzle game for iPhone and iPad.
childsplay - Childsplay is a collection of educational activities for young children and runs on Windows, OSX, and Linux. Childsplay can be used at home, kindergartens and pre-schools.